Here is my setup and situation. I have sensors on all my doors including garage door. I also have two motion sensors.

When we go away we will have someone come in and feed the cat and fish. They always enter through the garage door using the external key pad to open the door. When we are away any door opening or motion sensor sends notification.

I would like to have notifications turned off for a period of 15 minutes once the garage do is opened. Then after 15 minutes notifications would resume. This would prevent multiple notifications for someone feeding the animals when they open the garage door.

Yes this is possible, but I think (and correct me if I am wrong guys) that you will need a special SmartApp to do this work for you. Which will mean that you will need to code it or perhaps if a developer here likes the idea they might jump in and assist.

I think the best way would be through a SmartApp for this sort of thing. It would allow you more control over the process you have in mind. It really should not be too difficult to create. But, I am still learning Groovy having come from VB and C#. Sometimes, I wish for the days of Assembly coding (as although you had to develop more code it was pretty straight forward)